We have described a phosphorus catalyst which allows for the transition metal-free transfer hydrogenation of azobenzene with ammonia borane (NH3BH3). Hydridophosphorane 1  is formed by the reaction of NH3BH3 with the planar, T-shaped phosphorus compound, 2.   Compound 1   is capable of transferring hydrogen to a variety of unsaturated organic species. The results of mechanistic studies into this hydrogen transfer will be discussed, including data on the hydricity and pka of compound 1  , as well as Hammett studies and kinetic isotope effects for the reaction. A rationale for the reactivity consistent with experimental observations will be discussed.

Nonmetal transfer hydrogenation with a catalytic phosphorus (III) compound

248th National Meeting (2014)

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